Chapter 11, Heart

Question 1

what are the 6 principle mechanisms that are the outcomes of cardiac problems?

Answer 1

1. Failure of the pump: systolic dysfunction or diastolic dysfunction.
2. obstruction of flow
3. regurgitation flow: backward flow due to valve problems.
4. Shunted flow: congenital or acquired defects
5. Disorder of cardiac conduction.
6. Rupture of the heart or major vessels

Question 2

What is CHF?

Answer 2

congestive heart failure: end stage of cardiac disease.

Congestive: (involving or produced by congestion of a part of the body.)

Question 3

what can prevent the heart from contracting or dilating properly?

Answer 3

Systolic: myocardial infraction (dead tissue)
Diastolic: Left ventricular hypertrophy, myocardial fibrosis, amyloid deposition, or constrictive pericarditis.

Question 4

what are forward and backward failures?

Answer 4

Inadequate cardiac output: forward failure

congestion in the veins returning to the heart: backward failure.

Question 5

how can the heart compensate for cardiac output?

Answer 5

• Frank-starling mechanisms: increased fiber stretch = increased force from the muscles. If this occurs its called: “compensated heart failure”. This causes the muscle to use more oxygen which will eventually reach a point where the muscle can no longer compensate “de-compensated heart failure”.
• Neurohumoral system activation: NE = increase heart rate, Renin-angiotensin-aldosterone = water retention, Atrial natriuretic peptide: balances out the renin-angiotensin.
• Myocardial structural changes (augmented muscle mass) Concentric HYPERTROPHY: ventricular wall thickness increases without an increase int he size of the chamber. In pressure overload the ventricle dilates but wall thickness could be increased, thus we use heart weight to determine the hypertrophy and not wall thickness.

Question 6

what are the problems that come with myocardium hypertrophy?

Answer 6

circulation of the coronaries does not expand in step with the expanding heart potentially leading to ischemia. altered patterns of gene expression reminiscent of fetal myocytes for the myosin heavy chain are produced.
aerobic exercise can increase the capillary density of the heart while weight lifting may not have the same beneficial affect.

Question 7

Left-sided heart failure, describe it?

Answer 7

ischemic heart disease, systemic hypertension, mitral or aortic valve disease, primary disease (amyloidosis).

Morphological affects: diminished systemic perfusion and back-pressure into the lungs.

Question 8

symptoms of the Left sided heart failure?

Answer 8

-DYSPNES: shortness of breath on exertion is the earliest sign. 
As the disease progresses the patients may experience dyspnes when recumbent, because lying down increases venous return from the legs and elevation of the diaphragm. (orthopnea) This is relieved when the patient is sitting.
Enlarged heart (cardiomegaly), tachycardia, 3 heart sound.
Atrial fibrillation can also develop limiting ventricular filling, and also causing thrombi formation.

Question 9

what renal compensations make things worse in the case of left ventricular hypertrophy?

Answer 9

Decreased renal perfusion activates the Renin-angiotensin-aldosterone axis increasing volume. This exacerbates the pulmonary edema.
if CHF is severe diminished cerebral perfusion may manifest as hypoxic encephalopathy marked by irritability, diminished cognition, and restlessness and can progress to stupor and coma.

Question 10

what is the usual cause of right-sided-heart failure?

Answer 10

usually associated with left sided heart failure causing back-pressure onto the right side of the heart.
Cor-pulmonale: due to thromboembolim, vasoconstriction (obstructive sleep apnea).

Question 11

what are the symptoms of right sided heart failure?

Answer 11

the back pressure in the liver will cause congestive hepatomegaly, (nutmeg liver) and the congestion in the portal circulation causes congestive splenomegaly (spleen enlargement).
Also seen: peripheral edema, pleural effusion, ascities (abdominal swelling).

Question 12

what are some of the problems with surgical intervention?

Answer 12

surgery may correct the hemodynamic abnormalities but the repaired heart may not be completely normal. Also some scar tissue remains which can lead to arrhythmia.

Question 13

when do most heart congenital defects develop?

Answer 13

90% of congenital heart defect have an unknown cause but mostly develop during 3-8th weeks when major cardiovascular structures develop.

Question 14

what are the 3 classes of malformations of the heart?

Answer 14

• malformations, causing a left-to-right shunt: low pressure pulmonary system is exposed to higher pressure. The high pressure causes proliferation of smooth muscle of the vessels increasing resistance causing the shunt to reverse.
• malformations, causing a right-to-left shunt (cyanosis)
• malformations causing obstruction.

Question 15

what are the most common types of congenital cardiac malformations.

Answer 15

• atrial septal defect (ASDs) This mostly increase only right ventricular and pulmonary outlfow volumes, while VSDs and PDAs cause both increased pulmonary blood flow and pressure.
• Ventricular septal defect (VSDs)
• Patent ductus arteriosus (PDA). Septum primum and septum secundum fail to fuse to occulde the hole that form in the atrial walls; (ostium primum and secundum).

Question 16

what can prolonged right to left shunt cause?

Answer 16

Eisenmenger syndrome? due to increased pulmonary resistance. Eventually the condition is irreversible.

Question 17

where do VSD (ventricular septal defect) form and what are they associated with?

Answer 17

the left-to-right shunting is caused by a defect in the thinner membranous partition that grows downward from the endocardial cushions is responsible for 90% of VSD, most close spontaneously during childhood. but only 20-30% of VSDs occur in isolation, others are associated with other cardiac malformations.

Question 18

What are the clinical features of patent ductus arteriosus?

Answer 18

The ductus arteriosus closes on its own with prostalgandin E2., which can be administered to close it. PDA;s are high pressure left-to-right shunts that produce harsh, machinery-like murmurs. Normally no symptoms occurs but larger defects eventually can lead to eisenmenger syndrome with cyanosis and congestive heart failure.

Question 19

what are the clinical signs of Right-to-left shunts?

Answer 19

-distinguished by early cyanosis since O2 poor blood goes into the systemic circulation.
-Tetralogy of Fallot
-transposition of the great vessels.
Clubbing of the tips of the fingers and toes is seen. (hypertrophic osteoarthropathy) polycythemia, paradoxical embolization.

Question 20

what are the 4 defects seen in tetrology of fallot?

Answer 20

1. VSD (ventricular septal defect)
2. Right ventricular outflow tract obstruction (subpulmonic stenosis)
3. overriding of the VSD by the aorta (aortic valve lies just above the VSD, thus is a major site of egress for blood flow from both ventricles)
4. Right ventricular hypertrophy

All this leads to abnormal anterosuperior displacement of the infundibular septum leading to abnormal septation between the pulmonary trunk and aortic root.
The slight pulmonary stenosis protects the pulmonary circulation from the high pressure of the left ventricle. this prevents right ventricular failure.

Question 21

What is transposition of great arteries (right to left shunts)

Answer 21

abnormal formation of the truncal and aortopulmonary septa sot hat the aorta arises from the right ventricle and the pulmonary artery emanates from the left ventricle.
This is incompatible with life unless there is a VSD. 1/3 of cases VSD does develop.
Patent foramen ovale may also be seen but this may close requiring emergency surgical intervention.

Question 22

Describe aortic coarctation?

Answer 22

narrowing or constriction of the aorta. 2 forms:

1. Infantile preductual from featuring hypoplasia of the aortic arch proximal to the PDA
2. Adult postductal form consisting of a discrete ridgelike infolding of the aorta, adjacent to the ligamentum arteriosum.

• Preductal: with a PDA cyanosis is localized to the lower half of the body, without interventions most infants die in the neonatal period.
• Postductal: usually asymptomatic: upper extremity hypertension and hypotension in the lower extremities with weak pulses.

Question 23

what is ischemic heart disease synonymous with?

Answer 23

-Coronary artery disease (CAD)

Question 24

what are some of the causes of ischemic heart disease?

Answer 24

disbalance between blood supply and demand of the heart.

• increased demand
• diminished blood volume (hypotension or shock)
• diminished oxygenation (penumonia)
• diminished oxygen-carrying capacity (anemia, CO poisoning)

Question 25

what are the clinical symptoms of cardiac ischemia?

IHD = ischemic heart disease

Answer 25

• Angina pectoris (chest pain), can be stable (pain during excretion, predictable) or unstable (occurs at rest at random times).
• myocardial infraction: severity or duration is ischemia is sufficient
• Chronic IHD with CHF: progressive cardiac decompensation which occurs after acute MI or secondary to accumulated small ischemic insults, pump failure can occur.
• Sudden cardiac death (SCD): tissue damage from MI, lethal arrhythmia can occur without myocyte necrosis.

acute coronary syndrome is applied to any of the 3 manifestations of IHD; unstable angina, MI and SCD.

Question 26

what is critical stenosis?

Answer 26

when a plaque occluded 70% of the coronary vessels. Below 70% the symptoms are seen during exertion.

Question 27

what role does inflammation play in all stages of atherosclerosis?

Answer 27

Endothelial cells interact with circulating leukocytes resulting in T_cell and macrophages recruitment and activation. These cell drive smooth muscle cell accumulation and proliferation with associated matrix production superimposed on an atheromatous core of lipid cholesterol, calcification, and necrotic debris. Destabilization of the plaque can occur through macrophage metalloproteinase secretion.

Question 28

what can happen to a plaque in the coronary artery?

Answer 28

-Rupture, fissuring or ulceration of plaques can expose a thrombogenic surface below. leading to rapid thrombosis, hemorrhage into the core of plaques can expand plaque volume, thereby acutely exacerbating the degree of luminal occlusion.

Question 29

what factors determine if a plaque in an artery ruptures?

Answer 29

blood pressure, platelet reactivity, plaque composition.

1. thin fibrous core are more likely to rupture. Fissures frequently occur at the junction of the fibrous cap and the adjacent normal plaque-free arterial segment where the mechanical stresses are high and the fibrous cap is thinnest.
2. androgenic stimulation due to emotional stress can cause vasospasm.

Question 30

types of agina pectoris?

Answer 30

• typical/stable angina: occurs predictably during exertion
• Pinzmetal or variant angina: occurs at rest and is caused by coronary artery spasm (treated with vasodilators)
• Unstable angina: crescendo angina; increasingly frequent pain.

Question 31

process of coronary artery occlusion?

Answer 31

1. atheromatous plaque is eroded or suddenly disrupted by endothelial injury, intraplque hemorrhage, or mechnaicla foces
2. platelets adhere, aggregate and activated releasing Thromboxane A2 and ADP and serotonin causing platelet aggregation and vasospasm.
3. Activation of coagulation by exposure of TF
4. thrombus can evolve to completely occlude the coronary artery lumen.

Question 32

during coronary occlusion what damage occurs?

Answer 32

1. early changes are reversible
2. 20-40 minutes causes irreversible damage and coagulative necrosis of myocytes.
3. vessel injury eventually ensues.

Reperfusion injury could occur if circulation is restored. The myocardium could become stunned (noncontractile).

Question 33

Which coronary artery is dubbed the “widow maker”?

Answer 33

the proximal left anterior descending artery since it perfused so much.

Question 34

Describe transmural infractions? what other forms of infractions are there?

Answer 34

affect the entire heart thickness. ST segment elevations and can have negative Q waves with loss of R wave amplitude. STEMI: ST-segment elevatied MI.

Subendocardial infractions: only involve the endocardium (non-STEMI).

Microscopic infarcts: small-vessel occlusions. setting of vasculitis, embolization of valve vegetations or mural thrombi or vessel spasm due to catecholamines (emotional stress) can cause it as well as tumors.

Question 35

what are “wavy fibers”

Answer 35

seen microscopically on the edges of a MI whey reflect the stretching and buckling of noncontractile dead fibers.

Question 36

in what direction does MI heal?

Answer 36

from the edges to the center, so a larger one may not heal as well as a smaller MI.

Question 37

during MI why does hypercontracture occur?

Answer 37

intracellular levels of calcium increase as a result of impaired calcium cycling and sarcolemmal damage due to ischemia.

Question 38

what do we test in the blood if we are checking MI?

Answer 38

myoglobin, cardiac troponins T and I (TnT, TnI), creatine kinase (CK-MB) myocardial isoform, lactate dehydrogenase.

CK-MB levels rise in 2-4 hours after MI pear at 24-48. return to normal in 72 hours.

Troponin levels remain elevated for upto 10 days.

Question 39

at what point is myocardial rupture most likely to occur?

Answer 39

3-7 days when the damaged myocardium is replaced by soft friable granulation tissues.

Question 40

why do people with posterior MI have worse prognosis?

Answer 40

posterior transmural infarcts are more likely to be complicated by conduction blocks. Patients with anterior infractions have a much more guarded prognosis than those with posterior infraction.

Question 41

describe chronic ischemic heart disease?

Answer 41

called ischemic cardiomyopathy; progressive heart failure secondary to ischemic myocardial damage.

Question 42

what is considered hypertensive blood pressure?

Answer 42

140/90mmHg as if this is sufficiently prolonged it induces left ventricular hypertrophy.

Question 43

what can be seen microscopically in the hypertrophy heart muscle nuclei?

Answer 43

transverse diameter of myocytes is increased and there is prominent nuclear enlargement and hyperchromasia (boxcar nuceli) as well as intercellular fibrosis.

Question 44

when do we see artherosclerotic plaques in the pulmonary circulation.

Answer 44

-during cor pulmonale as a result of pulmonary hypertension the pulmonary arteries often contain atheromatous plaques and the lesions reflecting the long standing high pressure.

Question 45

Valvular heart disease description?

Answer 45

Stenosis: failure of the valve to open completely obstructing forward flow.
Insufficiency: failure of the valve to close properly therefore causing regurgitation (backflow). It can result from either intrinsic disease of the valve cusps (endocarditis) or disruption of the supporting structures (aorta mitral annulus, tendinous cords, papillary muscles, ventricular free wall without primary cuspal injury.

these two can occur together in the same valve.

Question 46

how can we diagnose diseased valves?

Answer 46

the turbulent flow through diseased valves typically produced abnormal heart sounds called Murmurs. extreme forms can also be palpated externally as Thrills.
Location of the murmur heard can determine which valve is affected. Timing: harsh systolic or soft diastolic.

Congential defects such as bicuspid aortic valves (instead of the normal 3 cusps) can create problems later in life as they may be more prone to early progressive degenerative calcification that gives rise to stenosis. The cusps can be of unequal size.

Question 47

Name the 4 degenerative valve diseases?

Answer 47

• calcifications: can be annular or cuspal. Mitral annular calcification is usually asymptomatic unless it encroaches on the adjacent conduction system.
• Alterations in the ECM: example: valves becomes fibrotic and scarred.
• Changes in the production of the matrix metalloproteinases or their inhibitors.
• Degenerative changes int he cardiac valves (unavoidable with age).

Question 48

Define myxomatous mitral valve?

Answer 48

floppy mitral leaflets prolapse they balloon back into the left atrium during systole. Primary mitral valve prolapse..they balloon back int he left atrium during systole.
Primary myxomatous degeneration cause is unknown but possible due to connective tissue remodeling. Thus it is a common feature of marfan syndrome (fibrillin-1 mutation).
Secondary myxomatous change presumably results from injury to the valve myofibroblasts, imposed by chronically aberrant hemodynamic forces.

Question 49

what are the microscopical changes to valves during myxoma?

Answer 49

Mitral valve is ballooned.
-Fibrosa layers of the valves are thinned of which the structural integrity of the leaflet depends accompanied by expansion of the middle spongiosa layer owing to increased deposition of myxomatous (mucoid) material.

Question 50

clinical course of myxoma?

Answer 50

A click and be heart when the valves close due to the abrupt tension on the valve leaflets and chordae tendinease.
3% of patients develop complications such as hemodynamically significant mitral regurgitation and CHF. (chronic heart failure).

Question 51

How does Rheumatic fever (acute immunologically mediated inflammation)

Answer 51

while the disease affects other organs it can affect the valves too.
Deformation of the fibrotic mitral stenosis, and it is thus the only form of acquired mitral stenosis.

This is caused by antibodies directed against group A streptococcal molecules that cross-react with host myocardial antigens.

Question 52

what are caterpillar cells?

Answer 52

anitschkow cells have abundant cytoplasm and nuclei with chromatin that is centrally condensed into a slender, wavy ribbon. Aschoff bodies can be found in all 3 layers of the heart. Thus rheumatic fever is said to cause pancarditis.
In chronic state the bodies are replaced by fibrotic tissue.
valve leaflets become thickened commissural fusion and shortening and thickening and fusion of the chordae tendineae.
Mitral valve is most affected with stenosis and insufficiency.

Question 53

Describe infective endocarditis

Answer 53

infective endocarditis (IE) is a microbial infection of the heart valves or the mural endocardium that leads to the formation of vegetations composed of thrombotic debris and organisms, often associated with destruction of the underlying cardiac tissues.
Prostatic devices also may become infected.
disease is classified as acute or subacute.
-acute: aggressive destructive infections which can be highly lethal even with treatment. High virulence bacteria attaching previously normal valve.
-subacute: low virulence organisms affecting previously abnormal heart (can be treated with antibiotics.)

streptococcus viridans found in oral flora can cause this disease.

Question 54

what are the major forms of vegetative endocarditits?

Answer 54

1. Acute rheumatic heart disease (RHD): small wary, inflammatory vegetations along the lines of valve closure, scarring can result as inflammation resolves.
2. Infective endocarditis (IE): large irregular often destructive masses that can extend from valve leaflets onto adjacent structures (chordae or myocardium)
3. Non-bacterial thrombotic endocarditis (NBTE) typically manifests with small to medium-sized bland nondestructive vegetations at the line of valve closure.
4. Libman-Sacks endocarditis (LSE): characterized by inflammatory vegetation that can be attached on either side of the valve leaflets, these heal with scarring.

Question 55

Describe noninflected vegetations on the valves of the heart?

Answer 55

(NBTE) non-infective bacterial endocarditis. is chatacterized by the deposition of sterile thrombi on cardiac valves, typically in those with an underlying hypercoagulable state.
These are NON-destructive. valve damage is not a prerequisite. can occur on previously normal valves.
While it has little affect on the valves it can however become infected and can form emboli to cause infarcts in the brain, heart and other organs. If colonized by bacteria it can become infective endocarditis.

Question 56

Libman sacks endocarditis description?

Answer 56

presence of sterile vegetations on the valves of patients with systemic lupus erythematosus. They develop as a consequence of immune complex deposition and thus exhibit associated inflammation, firbinoid necrosis of the valve adjacent to the vegetation.

Question 57

Describe cardiomyopathies and myocarditis?

Answer 57

Cardiac diseases due to intrinsic myocardial dysfunction are termed cardiomyopathies (heart muscle diseases)
Primary: principally confined to the myocardium
Secondary: presenting as the cardiac manifestation of a systemic disorder.

Question 58

what are the 3 types of cardiomyopathies that are recognized?

Answer 58

1. dilated cardiomyopathy (DCM) (arrhythmogenic right ventricular cardiomyopathy)
2. Hypertrophic cardiomyopathy (HCM)
3. Restrictive cardiomyopathy

Question 59

Describe Dilated cardiomyopathy?

Answer 59

is characterized by progressive cardiac dilation and contractile (systolic dysfunction).

Question 60

what are the causes of dilated cardiomyopathy?

Answer 60

• myocarditis
• alcohol or other toxic exposure
• genetic (cytoskeleton mutation) autosomal dominant
• peripartum cardiomyopathy (pregnancy). do to volume overload, nutritional deficiency.
• Iron overload (stimulates causing restrictive cardiomyopathy but dilation of ventricles is attributed to interference with metal-dependent enzyme systems or injury caused by iron-mediated production of ROS.)

Question 61

what are the clinical symptoms of dilated cardiomyopathy?

Answer 61

-ineffective contraction
-secondary mitral regurgitation and abnormal cardiac rhythms are common. Mural thrombi can occur
SIGNS: dyspnea, easy fatigability, poor exertion capacity.
Death is caused by arrhythmia usually.

Question 62

Describe arrhythmogenic right ventricular cardiomyopathy?

Answer 62

autosomal dominant disorder that classically manifests with right sided heart failure and rhythm disturbances, which can cause sudden cardiac death.
RIght ventricular wall is thinned due to fatty infiltration and some fibrosis. This is do to genetic coding desmosomal junctional proteins at the intercalated discs.

Question 63

Describe hypertrophic cardiomyopathy? (HCM)

Answer 63

myocardial hypertrophy, defective diastolic filling and ventricular outflow obstruction.
usually caused by missence mutations. The mutation involves sarcomeric proteins. Beta-myosin heavy chain and myosin binding protein C and troponin T are frequently mutated. This cause hypercontractility increased energy use and net negative energy balance.

Question 64

clinical symptoms of hypertorphic cardiomyopathy?

Answer 64

hard edjection murmur. There is also hypertrophy of the left side of the heart but a paradoxically decreased cardiac output as a result of the smaller lumen of the ventricle.pulmonary venous pressure increases, causing exertional dyspnea.
atrail fibrillation and mural thrombus formation and ventricular fibrillation can occur leading to sudden cardiac death.

Question 65

describe restrictive cardiomyopathy?

Answer 65

characterized by a primary decrease in ventricular compliance, resulting in impaired ventricular filling during diastole (the wall is stiffer). Can be idopathic.

• Amyloidosis: insoluble B-pleated sheets. Can be systemic (multiple myeloma) or restricted to the heart. In the latter case transthyretin (liver protein for thyroxine and retinol) in the heart tissue.
• endomyocardial fibrosis (linked to nutritional deficiencies and inflammation)
• loeffler endomyocarditis: firbosis of the endocardium hypereosinophilia and eosinophilic tissue infiltrates, release of eosinophil granule contents , especially major basic protein.

Question 66

Describe the clinical features of pericardial disease?

Answer 66

chest pain is seen that is NOT related to exertion and worse in recumbency. and a prominent friction rub. Fluid accumulation causing cardiac tamponade which decreased cardiac output.

Question 67

Describe the cardiac tumors: myxomas and rhabdomyomas

Answer 67

Myxomas: primary tumors of the adult heart (80% occur in the atrium) Surgical resection can cure it.
Rhabdomyomas: most frequent primary tumors. They are frequently associated with valvular or outflow obstruction. it occurs in high frequency in patients with tumor suppressor genes loss TSC-1 and TSC-2.
They show up as Gray-white masses showing mixed population of cells: polygonal cells containing numerous glycogen-laden vacuoles separated by strands of cytoplasm running from the plasma membrane to the centrally located nucleus called “spider cells”.